Since the first introduction of a composite resin dental material filling syringe, such as the one disclosed in U.S. Pat. No. 3,581,399 entitled "Composite Resin Filling Syringe and Technique" issuing to Dragan on Jun. 1, 1971, there have been many improvements thereto. These improvements often related to the cartridge o tip containing the dental filling material used within a syringe, gun, or extruding device.
Two examples of improved dental cartridges can be found in U.S. Pat. No. 4,391,590 entitled "Cartridge for Viscous Material" issuing to Dougherty on Jul. 5, 1983 and U.S. Pat. No. 4,963,093 entitled "Dental Syringe Tip and Syringe Holder Therefor" issuing to Dragan on Oct. 16, 1990. Both of these patents disclose a cartridge or tip to be placed in a syringe for extruding the dental material contained within the cartridge or tip. They both relate to an opaque cartridge having a first linear axis for the reservoir or body portion and a second linear axis for the nozzle discharge portion. Both cartridges are additionally intended to contain a light sensitive dental material that will cure or harden when exposed to a specific wavelength of light. Therefore, the cartridges are intended to be pre-loaded in a controlled environment for subsequent distribution to the dentist. The dentist then dispenses the dental material contained therein in a single application.
While these cartridges or tips are appropriate for some applications, they are not desirable in many others. In many applications, the dentist may wish to fill his own cartridges for dispensing dental material of his own choice. It is often difficult to fill, by hand, an unfilled opaque cartridge. This is because of the inability to see the material being placed therein. Additionally, it is difficult to determine the quantity or volume of material being placed within an opaque cartridge. In many instances, a dentist may not require or desire a full cartridge. Additionally, the straight cartridge having a relatively large end in relation to the nozzle portion makes visibility difficult in the small and confining areas of the mouth where the dentist must work. Also, consistency of material is of primary concern in the application of dental material in a cavity. In the cartridges having multiple axes and a change of direction of material flow, often turbulence or air entrapment can result. This is very undesirable in that voids or inconsistency of material compromises the integrity of the filling. Further, the dental material being relatively expensive, it is undesirable to leave any dental material remaining within the cartridge. The material is often left in the discharge nozzle portion that is at an angle to the body portion.
As should be readily appreciated from the above, there are many instances in which an improved dental cartridge is needed to provide better dental care at a reduced cost.